The present invention relates to a device for use at the ear of a user for alerting the user against dozing.
Dozing can be dangerous in certain situations, such as when a person is driving a car. Doze alerting devices of the type concerned for use at the ears should have been known in general, but the very few ones known are found to have shortcomings. For example in one such device, a mercury switch is used as a gravity sensor to detect the lowering of a user""s head when the user starts to doze, but mercury switches tend to be bulky and are not safe by nature. In general, all such devices are inconvenient to use because they are designed for use at one particular left or right ear of the users and their sensitivity can hardly be adjusted.
The invention seeks to mitigate or at least alleviate such shortcomings by providing an improved doze alerting device.
According to the invention, there is provided a doze alerting device comprising a casing, an earplug connected with the casing, said earplug being insertable selectively into either one of the left and right ears, as desired, of a user to locate the casing on the head of said user at a desired angular position relative thereto, and an internal electronic operating circuit. The operating circuit incorporates an audio generator for generating a doze-alert audio signal for said user and a gravity switch for triggering the audio generator. The gravity switch has first and second solid electrical contacts for switching on or off to trigger the audio generator, with the second contact being movable under the action of gravity along a defined path towards and away from the first contact to perform switching. The path is fixed relative to the casing for simultaneous angular movement therewith such that the gravity switch will provide a trigger signal when the casing moves from a first angular position corresponding to an upright position of said head when said user is looking straight ahead to a second angular position corresponding to a dipped position of said head when said user starts to doze, with the path tilting to below the horizontal. The path is substantially linear such that the doze alerting device can be used at either the left or the right ear of said user without any material effect on the angular positioning of the casing and the operation of the gravity switch.
Preferably, the earplug is fixedly connected to the casing and has a substantially circular shape such that it can be turned within said ear to adjust the angular position of the casing relative to said head.
Preferably, the casing is elongate and has a front end and a rear end, to which rear end the earplug is connected.
In a preferred embodiment, the casing has a longitudinally extending axis, and the path extends substantially parallel to the axis.
More preferably, the casing has a substantially symmetrical shape on opposite sides about its axis.
It is further preferred that the casing has a plane of substantial symmetry along its axis, and the path lies in that plane.
It is further preferred that the earplug has a substantially circular shape about a central axis, which axis intersects with that of the casing such that the casing and the earplug share a common plane of substantial symmetry.
It is preferred that the audio generator is implemented based on an IC chip and includes a buzzer.
In a preferred embodiment, the gravity switch has a elongate body encasing the second contact and defining the path for the second contact.
More preferably, the body comprises a tube having a circular cross-section and the second contact is in the form of a ball.
More preferably, the first contact and a third solid electrical contact of the gravity switch are fixed at opposite ends of the body to provide two terminals. The body includes an inner surface which is electrically conductive and in electrical connection with the third contact and with which the second contact is in continuous sliding electrical contact.